The present invention is hereinafter explained with reference to dental surgery. However the applications of the present invention are not limited to dental surgery only, and in fact include any surgery involving the use of a medical tool, which is intended to penetrate into tissue and bone such as in orthopedics, general surgery and other such fields.
For planning an implantation procedure, which is performed by an oral and maxillofacial surgeon, in the mandible or the maxilla, the patient undergoes an x-ray imaging, computer tomography (CT) and a panoramic imaging. From these images, the surgeon is able to plan the implantation procedure and also to take-out the data about the mandible, such as the depth of the canal that contains the nerve and the thickness of this bone. These imaging methods do not provide the surgeon with required information in real time, concerned with the distance between the bottom part of the drill and the top part of the canal that contains the nerve.
The present invention completes the information obtained by the CT and the panoramic imaging, by guiding the surgeon during the drilling process thus enhancing prevention of injuries during the surgery. It provides a method and device for measuring the distance between the bottom part of a dental drill and vulnerable parts (such as the canal that contains the nerve in the lower mandible) in a patient's bone during an implantation surgery process. For example, the invention can be integrated into a dental drill to provide the dental surgeon with real time guiding location of the drill tip in the patient's bone during implantation surgery.
With the present invention the surgeon can know where the drill tip is relative to sensitive areas of the patient's bone. This improves the efficiency, safety and reliability of the surgical procedure, particularly in cases where the depth of the drill must be carefully monitored and guided, in order to prevent injury to vulnerable areas in the bone, such as nerves or blood vessels that lie on the drill's path.
The present invention measures the location of the bottom of the drill relative to the surrounding bone by means of ultrasound (US) radiation and makes that information immediately available to the surgeon. The ultrasound is transmitted and received via the jet of liquid running from the drill.
US transmission through a liquid jet was described as a confirmation sensor of a drill in its position in a drilling machine (U.S. Pat. No. 5,850,184), as a dental tool for removing plaque from teeth and for cleaning teeth (U.S. Pat. No. 5,013,241), a high velocity pulsating jet stream for the removal of the dental plaque (U.S. Pat. No. 4,012,842), A thermal imaging system for detecting cracks in tooth, by applying an US dental cleaning tool that transmits US energy through a jet of water to the tooth. This causes cracks in the tooth to heat up and a thermal camera is used to detect the thermal radiation emitted by the heated cracks (U.S. Pat. No. 6,437,334B1).
Another possibility is to sweep angularly with the jet of water that carries the US, and by this one is able to obtain an image of a section or of a volume.
US radiation is a proven technology used in many medical diagnostic applications and was also applied for bone diagnostics—density, structure and velocity of propagation (U.S. Pat. No. 6,030,221, U.S. Pat. No. 5,006,984, U.S. Pat. No. 5,115,813, U.S. Pat. No. 5,402,781, U.S. Pat. No. 5,518,008, U.S. Pat. No. 5,564,423, U.S. Pat. No. 5,651,363). These parameters are important in order to investigate the correct value of the distance mentioned earlier. The radiation levels applied during the use of the present invention are in an accepted range for diagnosis and therefore pose no harm to the patient or the surgeon. Temperature gradients of the radiated area are negligible, especially when the US radiation is transmitted via a liquid jet as in the case of the present invention.
The present invention is particularly advantageous for surgery where depth measurements in the mandible and the maxilla are required, as for example, in mandible intra-osseous implantations.
Another advantage of the present invention for such surgery is that the US radiation is applied through an existing jet of liquid (usually distilled water) flowing from the dental tool. Therefore no additional medium is required, keeping the dimensions of the drill fitted with present invention small and well suited for work within restricted volumes, like the mouth.
The present invention provides the surgeon with real-time information; is relatively inexpensive compared to other, less satisfactory imaging alternatives; and saves time for both the patient and the surgeon (since there is no need to move imaging equipment in and out or to interrupt the surgical procedure).
In summary, it is a main object of the present invention to provide a probe for use in dental surgery for measuring distance from a bottom of a drill to surrounding bone, the probe provided with a mechanism for transmitting and receiving ultrasonic signals, a mechanism for processing the ultrasonic signals to determine the distance to the tissue, and a mechanism for communicating that information to the surgeon.